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clutch
01-14-2010, 10:11 PM
I'm having issues visualizing just what shape I need to grind on a HSS blank to fit the 45 degree angle through hole of my boring bar. Anyone got pictures?

Clutch

Carld
01-14-2010, 11:50 PM
I will post some photo's tomorrow, it's to late now.

Black_Moons
01-14-2010, 11:57 PM
Clutch: Depends what you wanna do :)
Do you wanna thread? Groove? Turn inside diamiters? Face the bottom of blind holes? Several of these with one tool?

Pertty much you just grind whatever form you need but at 45 degrees. Insure the bit is long enough to extend past the end of the boring bar if you plan to use it to face holes or turn to a blind bottom.

How small of a diamiter are you boring? that will influance how much relief your tool must have, and how much you should try and 'round' the bottom of the bit (a round relief works better as it gives more support and more clearance where it matters)

oldtiffie
01-15-2010, 12:00 AM
Put the square (or round?) tool-bit in the 45 degree hole in the boring bar.

Have some of the bit sticking out of the bar and clamp it.

Then grind the tool as normal to the shape you want.

Carld
01-15-2010, 12:14 AM
I lied, here is some cutters.

http://i82.photobucket.com/albums/j276/yeathatshim/P1150002.jpg

I use the standard V nose cutter most the time but sometimes I use a left hand cutter and grind it as shown in the second tool from the top. The first tool is one that is not ground for comparison. You should be able to see what is ground away to use it. Also, don't forget to grind a radius on the side of the tool that is in line with the bore for clearance. The clearance has to be less than the diameter of the bore.

Evan
01-15-2010, 01:26 AM
Another little thing about boring bars: There is no rule about where they contact the work. You may find that it works better cutting at about the 10 or 11 o'clock position since it will tend to push the carriage back and take up any play in the cross feed screw. Same idea but opposite for cutting on the bottom. Sometimes changing the point of contact can get rid of chatter. Of course this is a lot easier to manage with a round boring bar.

Boucher
01-15-2010, 02:09 PM
Get you some square wooden dowell and install it in the boring bar. Wood grinds easy to work out the pattern for what you need.

JCHannum
01-15-2010, 02:43 PM
Another little thing about boring bars: There is no rule about where they contact the work. You may find that it works better cutting at about the 10 or 11 o'clock position since it will tend to push the carriage back and take up any play in the cross feed screw. Same idea but opposite for cutting on the bottom. Sometimes changing the point of contact can get rid of chatter. Of course this is a lot easier to manage with a round boring bar.

While the position is less critical with respect to positive or negative rake, the cutter does need to be in the plane of the tool movement, ie, cross slide travel. If it is pointing up at 10:00 o'clock, it is not going to remove much material unless you have some means of feeding it in that direction.

Carld
01-15-2010, 03:13 PM
The other issue is, if the tip of the cutter is not at or near the center line .001" on the dial will not get .001" on the work.

You don't even want to know how I found this out and it was costly.

While I will tilt the bar up and down I seldom move the tip off center line.

Evan
01-15-2010, 03:45 PM
You are right about the cross feed dial but I rarely use it when doing something critical. I get close by eye and then start measuring, often with a tapered plug gauge for things like press fits.


If it is pointing up at 10:00 o'clock, it is not going to remove much material unless you have some means of feeding it in that direction.

Not so.

clutch
01-15-2010, 06:34 PM
I lied, here is some cutters.

http://i82.photobucket.com/albums/j276/yeathatshim/P1150002.jpg

I use the standard V nose cutter most the time but
[snip]



The one you have mounted in your bar is the grind I used. A bit more acute than 90 degrees. I'm used to using inserted carbide boring bars at work, supplied by work but since I'm doing hobby stuff at home, I'm exploring HSS and am having to learn a few things I don't know or did know and can't remember. That bit about forgetting things is the story of my life.

Black_Moon's, I'm boring the id of a L-00 spindle nose protector for a 5c collet drawbar setup I'm making.

Tomorrow, I'll grab the digicam and post what I came up with for a bit before I called out for help. It might be worth a laugh. ;)

Thanks,

Clutch

Boucher
01-16-2010, 07:25 PM
This is what a commercial version in the Everede bar looks like. I think this is a 30 bar but it conveys the basic configuration.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0064.jpg
This bar uses their Triangular shaped bit which is very easy to sharpen. You don't hear a lot about these bars but I really believe they are some of the best.

Hope this helps.